The Influence of Bond-pad Smear Crevices on IMC Corrosion in Cu-Al Bonds

Since the introduction of Cu wire-bonding in the semiconductor industry, corrosion of the Cu-Al intermetallics (IMCs) has been one of the main concerns in developing reliable products using this interconnect technology. Much insight has been gained in selecting suitable bill-of-materials, controlling levels of halides and pH, contamination control and controlling contamination ingress in the package, as well as creating ball bonds with high levels of Intermetallic coverage. But yet it is clear that other, many times unknown, factors also play a role. The work presented here attempts to shed more light on one other suspected factor, the crevice created between the ball bond and the bond-pads deformed splash.